Exchange system and communication recording method

ABSTRACT

A switching system capable of carrying out call recording without producing any reception delay in communication data. In this system, upon reception of a call connection request from a communication terminal  210,  a call control apparatus  250  selects a multicast address, notifies the multicast address to all communication terminals  230  involving in the call connection and joins a multicast group indicated by the address. The communication terminal  210  transmits all voice data of the call using the address while the call is connected and the call control apparatus  250  mixes the voice packet directed to the own apparatus sent to the address and stores the voice packet in a user data voice storage database  160.

TECHNICAL FIELD

The present invention relates to a switching system which switches voicecommunications carried out between communication terminals through theInternet and LAN, etc., and a call recording method for recording thecontents of a call, and more particularly, to a switching system capableof recording a call without causing any reception delay of voice data.

BACKGROUND ART

In recent years, the Internet is becoming accessible from not only apersonal computer but also a home device such as a telephone terminal,and the Internet is thereby becoming widespread at an accelerating pace.

The Internet has been conventionally used as a network fortransmitting/receiving character information and image information, butrecently great attention is being focused on an Internet telephone whichtransmits voice information using the Internet. This is because theInternet telephone is not constrained by a conventional system ofbilling in proportion to distance and has advantages such as the abilityto communicate with people overseas at a low price.

However, while the telephone network is a network dedicated to voicedata transmission, an IP (Internet Protocol) network transmits not onlyvoice data but also other data and a conversation between telephoneterminals through the IP network may become unnatural due to atransmission delay of the voice data. For this reason, it is necessaryto avoid reception delays of voice data so that voice data of a call canbe transmitted in real time.

Furthermore, conventional offices introduce a PBX (Private BranchExchange) to realize various telephone services using a telephonenetwork. Thus, when an IP network is used, the IP network is required torealize various telephone services covered by the PBX so far.

One of services of the PBX is call recording. In conventional callrecording, voice data of a call between telephone terminals incommunication is recorded in an external storage medium in the PBX orconnected to the PBX.

On the other hand, a system of call recording using an Internettelephone is disclosed in the Unexamined Japanese Patent Publication No.2000-201237. In this system, an Internet telephone apparatus connectedto an IP network and PSTN (Public Switched Telephone Network) networksends downlink voice data sent from the IP network to the PSTN network,sends uplink voice data sent from the PSTN network to the IP network,combines the downlink voice data sent from the IP network and the uplinkvoice data sent from the PSTN network and stores the voice data in acall recording apparatus.

Using this Internet telephone apparatus as a call control apparatus, itis possible to construct a switching system shown in FIG. 1. This systemincludes a call control apparatus 6 provided with a voice storagedatabase (DB) 7, communication terminals 2 an 4, a network 8 such as theInternet and LAN and switches 1, 3 and 5 to send a received packet to adestination IP address.

The switches 1, 3 and 5 compare the destination IP address of a receivedpacket with an internal address table and send the packet to a portconnected to a destination communication terminal.

The communication terminals 2 and 4 are telephone terminals such asInternet telephones or IP telephones connected to a network.

The call control apparatus 6 controls a call connection status such as“BUSY” of a communication terminal connected to the network and switchesbetween bidirectional voice data of a call between communicationterminals in communication. For example, voice data from thecommunication terminal 2 is switched to the communication terminal 4 oron the contrary, voice data from the communication terminal 4 isswitched to the communication terminal 2. Then, the bidirectional voicedata is mixed and stored in the voice storage database 7.

The network 8 is the Internet, LAN (Local Area Network) or an IP networksuch as IP-VPN (Internet Protocol-Virtual Private Network).

The switches 1, 3 and 5 may also be apparatuses having a router functionfor carrying out routing according to IP addresses depending on the typeof the network 8.

Reference numerals “9” and “10” in FIG. 1 denote voice paths between thecommunication terminals 2 and 4 when a call is connected in thisswitching system, the voice path 9 shows the voice path of voice datasent from the communication terminal 4, switched at the call controlapparatus 6 and received by the communication terminal 2 and the voicepath 10 shows the reverse voice path.

In this system, when the communication terminal 2 dials a call to thecommunication terminal 4 on the other end, a call connection request issent to the call connection apparatus 6. When the call connectionapparatus 6 decides that the communication terminal 4 can receive thecall, it notifies the communication terminal 4 of the call connectionrequest from the communication terminal 2. In this way, preparationsnecessary for the call connection are made between the communicationterminal 2 and communication terminal 4, negotiation and settings aboutthe terminal capacity such as voice codec are performed and then thecall is connected, that is, a conversation can be held.

The call control apparatus 6 switches bidirectional voice data betweenthe communication terminals 2 and 4 (see voice paths 9 and 10) allowinga conversation between the communication terminals to be held, performsvoice mixing at the same time as the switching, stores the voice data ofthe call in the voice storage database 7 and records the call.

However, since this conventional switching system is constructed in sucha way that voice paths in both directions necessarily pass through thecall control apparatus 6 to realize call recording, the followingproblems result.

When the network 8 is a large scale network, there are many routers andswitches on the network 8 from the call control apparatus 6 to therespective communication terminals 2 and 4 and it takes a considerabletime until the voice data sent from the call control apparatus 6 isreceived by the communication terminal 2 or 4. This increases the timeinterval between transmission of the voice data and reception of thevoice data and the conversation between the communication terminals 2and 4 becomes unnatural such as the voice of the party on the other endbeing heard with a delay. Even if the network operator designs anoptimal route within the network 8, such an improvement has certainlimitation.

Furthermore, when the call control apparatus 6 switches voice data asdescribed above, the number of communication terminals that can becontrolled by the call control apparatus 6 decreases for reasons relatedto the performance (processing capacity) of the call control apparatus6.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a switching systemand call recording method capable of carrying out call recording withoutproducing any reception delay of communication data.

The switching system according to one aspect of the present invention isa switching system that connects a plurality of communication terminalsby the medium of a call control apparatus having a call recordingfunction through a network, each of the plurality of communicationterminals comprising a generation section that generates a plurality ofcopies of the same voice data while a call is connected and atransmission section that transmits one of the plurality of copies ofthe same voice data to the communication terminal on the other end asvoice data for conversation and transmits another one to the callcontrol apparatus as voice data for call recording, and the call controlapparatus comprising a notification section that notifies the pluralityof communication terminals of the destination address of the voice datafor call recording and a mixing/storage section that mixes and storesthe voice data for call recording sent to the respective destinationaddresses of the plurality of communication terminals.

Another aspect of the present invention is a call recording method in aswitching system that connects a plurality of communication terminals bythe medium of a call control apparatus having a call recording functionthrough a network, comprising a notifying step of the call controlapparatus notifying the plurality of communication terminals of thedestination address of the voice data for call recording, a generatingstep of the plurality of communication terminals generating a pluralityof copies of the same voice data while a call is connected, atransmitting step of the plurality of communication terminalstransmitting one of the plurality of copies of the same voice datagenerated in the generating step to the communication terminal on theother end as voice data for conversation and transmitting another one tothe call control apparatus as voice data for call recording and amixing/storing step of the call control apparatus mixing and storingvoice data for call recording sent from the plurality of communicationterminals to the destination addresses.

The switching system according to a further aspect of the presentinvention is a switching system that connects a plurality ofcommunication terminals by the medium of a call control apparatus havinga call recording function through a network, each of the plurality ofcommunication terminals comprising a first acquisition section thatacquires a multicast address and a formation section that forms voicepaths through multicasting to transmit/receive voice data to/from thecommunication terminal on the other end based on the acquired multicastaddress, the call control apparatus comprising a notification sectionthat notifies the plurality of communication terminals of the multicastaddress, a second acquisition section that acquires the voice data sentfrom the plurality of communication terminals through the multicastingby joining the multicast and a mixing/storage section that mixes andstores the acquired voice data.

The call recording method according to a still further aspect of thepresent invention is a call recording method in a switching system thatconnects a plurality of communication terminals by the medium of a callcontrol apparatus having a call recording function through a network,comprising a notifying step of the call control apparatus notifying theplurality of communication terminals of a multicast address, a firstacquiring step of the plurality of communication terminals acquiring themulticast address notified from the call control apparatus, a formingstep of the plurality of communication terminals forming voice pathsthrough multicasting to transmit/receive voice data to/from thecommunication terminal on the other end based on the multicast addressacquired in the first acquiring step, a second acquiring step of thecall control apparatus acquiring voice data sent from each of theplurality of communication terminals through the multicasting by joiningthe multicasting and a mixing/storing step of the call control apparatusmixing and storing the voice data acquired by the second acquisitionsection.

The switching system according to a still further aspect of the presentinvention is a switching system that connects a plurality ofcommunication terminals by the medium of a call control apparatus havinga call recording function through a network, each of the plurality ofcommunication terminals comprising a buffer section that temporarilystores voice data to be sent to a communication terminal on the otherend while a call is connected or voice data received from thecommunication terminal on the other end and a transmission section thattransmits the voice data stored in the buffer section after adisconnection of the connected call to the call control apparatus asvoice data for call recording, the call control apparatus comprising anotification section that notifies the plurality of communicationterminals of the destination address of voice data for call recordingand the communication terminal address which is the destination of thevoice data for conversation and a mixing/storage section that mixes andstores the voice data for call recording sent from the plurality ofcommunication terminals to the destination address.

The call recording method according to a still further aspect of thepresent invention is a call recording method in a switching system thatconnects a plurality of communication terminals by the medium of a callcontrol apparatus having a call recording function through a network,comprising a notifying step of the call control apparatus notifying theplurality of communication terminals of the destination address of voicedata for call recording and the communication terminal address which isthe destination of the voice data for conversation, a storing step ofthe plurality of communication terminals temporarily storing the voicedata to be sent to the communication terminal on the other end while acall is connected or voice data received from the communication terminalon the other end in a buffer section, a transmitting step of theplurality of communication terminals transmitting the voice data storedin the buffer section in the storing step after a disconnection of theconnected call to the call control apparatus as voice data for callrecording, a mixing/storing step of the call control apparatus mixingand storing the voice data for call recording sent from the plurality ofcommunication terminals to the respective destination addresses.

The switching system according to a still further aspect of the presentinvention is a switching system that connects a plurality ofcommunication terminals by the medium of a call control apparatus havinga call recording function through a network, each of the plurality ofcommunication terminals comprising a buffer section that temporarilystores voice data to be sent to a communication terminal on the otherend while a call is connected or voice data received from thecommunication terminal on the other end, a mixing section that mixes thevoice data stored in the buffer section after a disconnection of theconnected call and a transmission section that transmits the mixed voicedata to the call control apparatus as voice data for call recording, thecall control apparatus comprising a notification section that notifiesone of the plurality of communication terminals of the destinationaddress of voice data for call recording and the communication terminaladdress which is the destination of the voice data for conversation anda storage section that stores the voice data for call recording sentfrom the one of the plurality of communication terminals to thedestination address.

The call recording method according to a still further aspect of thepresent invention is a call recording method in a switching system thatconnects a plurality of communication terminals by the medium of a callcontrol apparatus having a call recording function through a network,comprising a notifying step of the call control apparatus notifying oneof the plurality of communication terminals of the destination addressof voice data for call recording and the communication terminal addresswhich is the destination of the voice data for conversation, a storingstep of one of the plurality of communication terminals temporarilystoring the voice data to be sent to the communication terminal on theother end while a call is connected and voice data received from thecommunication terminal on the other end in a buffer section, a mixingstep of the one of the plurality of communication terminals mixing thevoice data stored in the buffer section after a disconnection of theconnected call, a transmitting step of the one of the plurality ofcommunication terminals transmitting the voiced at a mixed in the mixingstep to the call control apparatus as voice data for call recording anda storing step of the call control apparatus storing the voice data forcall recording sent from one of the plurality of communication terminalsto the destination address.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates voice paths in a conventional switching system;

FIG. 2 is a block diagram of a switching system according to Embodiment1 of the present invention;

FIG. 3 illustrates an address control table according to Embodiment 1 ofthe present invention;

FIG. 4 illustrates a table stored in a user data voice storage databaseaccording to Embodiment 1 of the present invention;

FIG. 5 illustrates a sequence diagram showing operations of theswitching system according to Embodiment 1 of the present invention;

FIG. 6A illustrates a data structure of a connection request messageaccording to Embodiment 1 of the present invention;

FIG. 6B illustrates a data structure of a connection response messageaccording to Embodiment 1 of the present invention;

FIG. 7 illustrates voice paths of the switching system according toEmbodiment 1 of the present invention;

FIG. 8 illustrates a block diagram of a switching system according toEmbodiment 2 of the present invention;

FIG. 9 illustrates a multicast address control table according toEmbodiment 2 of the present invention;

FIG. 10 illustrates a table stored in a user data voice storage databaseaccording to Embodiment 2 of the present invention;

FIG. 11 is a sequence diagram illustrating operations of the switchingsystem according to Embodiment 2 of the present invention;

FIG. 12A illustrates a data structure of a connection request messageaccording to Embodiment 2 of the present invention;

FIG. 12B illustrates a data structure of a connection response messageaccording to Embodiment 2 of the present invention;

FIG. 13 illustrates voice paths of the switching system according toEmbodiment 2 of the present invention;

FIG. 14 is a block diagram of a switching system according to Embodiment3 of the present invention;

FIG. 15 is a sequence diagram showing operations of the switching systemaccording to Embodiment 3 of the present invention;

FIG. 16 illustrates voice paths of the switching system according toEmbodiment 3 of the present invention;

FIG. 17 illustrates a table stored in a user data voice storage databaseaccording to Embodiment 3 of the present invention;

FIG. 18 is a block diagram of a switching system according to Embodiment4 of the present invention;

FIG. 19 is a sequence diagram showing operations of the switching systemaccording to Embodiment 4 of the present invention;

FIG. 20 illustrates voice paths of the switching system according toEmbodiment 4 of the present invention; and

FIG. 21 illustrates a table stored in a user data voice storage databaseaccording to Embodiment 4 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference now to the attached drawings, embodiments of the presentinvention will be explained in detail below. The present invention isnot limited to these embodiments, but can be implemented in variousmodes without deviating from the spirit or essential characteristicthereof.

Embodiment 1

This embodiment will describe a system in which a communication terminalcreates two identical voice packets, sends one to a call controlapparatus and sends the other directly to a communication terminal onthe other end.

As shown in FIG. 2, this switching system includes a call controlapparatus 150 provided with a database which stores user data and voice(hereinafter referred to as “user data voice storage database”) 160,communication terminals 110 and 130 that carry out communicationsthrough a network 170 and switches 100, 120 and 140 that send receivedpackets according to their addresses, and the call control apparatus 150and communication terminals 110 and 130 are connected to the network 170through the switches 100, 120 and 140.

The switches 100, 120 and 140 compare the destination IP address of areceived packet with an internal address table and send the packet to aport to which the destination communication terminal is connected.

The communication terminals 110 and 130 are provided with communicationsections 111 and 131 that carry out all processing related totransmission/reception (communication) of voice data, playback section112 and 132 that carry out all processing related to playback of voicedata of a stored call, voice path control sections 113 and 133 thatcontrol the processing of creating two identical voice packets to betransmitted and transmitting the voice packets to the call controlapparatus and the party on the other end and communication terminaloverall control sections 114 and 134 that control the entirecommunication terminal.

When a call is connected and a conversation is started and when thevoice path control sections 113 and 133 packetize voice data from theown communication terminals 110 and 130 and send the packetized datathrough the communication section 111 and 131 over the network, thevoice path control sections 113 and 133 perform predetermined control soas to create two identical packets, send one to the call controlapparatus and send the other to the communication terminal of the partyon the other end.

The communication terminals 110 and 130 can be any terminals which atleast incorporate a communication function capable of accessing thenetwork and may be a personal computer (PC), Internet telephone and IPtelephone, etc.

The call control apparatus 150 is provided with a voice mixing section151 that mixes and stores packetized voice data sent from acommunication terminal with which a call is connected, a voice playbackcontrol section 152 that controls playback processing of voice datastored in the user data voice storage database 160 based on a playbackrequest from the communication terminal, a communication section 153that carries out communication processing with the communicationterminal, an address giving section 154 which sets and controlsaddresses when the communication terminals 110 and 130 send voice datato the call control apparatus 150 and a call control apparatus overallcontrol section 155 that controls the entire call control apparatus.

The communication section 153 processes transmission/reception ofvarious requests (e.g., call connection request) from the communicationterminal and performs communication processing such as generating voicedata from a received packet and sending voice data by packetizing it.

The call control apparatus overall control section 155 controls a callconnection status (busy or not) of a communication terminal which is atleast connected to the network and the address of the communicationterminal and when a call connection request is sent to the communicationterminal, the call control apparatus overall control section 155 decideswhether the connection is possible or not from the call connectionstatus under its control and enables the connection between thecommunication terminals when the connection is possible.

The user data voice storage database 160 connected to the call controlapparatus 150 stores voice data sent from the voice mixing section 151after mixing of voice data indicating the content of a conversation andextracts the stored voice data based on an instruction from the voiceplayback control section 152. Furthermore, the user data voice storagedatabase 160 controls a service registration status (e.g., informationon registration/no registration of call recording) of users who use thecommunication terminals 110 and 130.

The network 170 is the Internet, LAN and an IPnetwork such as IP-VPN.Furthermore, the switches 100, 120 and 140 may also be an apparatuswhich has at least a router function of performing routing using IPaddresses according to the type of the network 170.

The functions of the communication terminals 110 and 130 and callcontrol apparatus 150 are implemented by causing computers incorporatedin these apparatuses to execute processing specified by a program.

FIG. 3 shows a control table (reception address control table) ofreception addresses used to receive voice data from the communicationterminals 110 and 130 under the control of the address giving section154. As shown in FIG. 3, this control table consists of a voice datareception addresses and their utilization statuses.

FIG. 4 shows an example of contents controlled by the user data voicestorage database 160. As shown in FIG. 4, this user data voice storagedatabase 160 consists of a terminal type that indicates the type of acommunication terminal connected to the call control apparatus 150through the network 170, a service registration status that indicatesthe content of service registration of the user who owns thecommunication terminal and a storage area that stores call recordingswhich become effective when “CALL RECORDING REGISTERED” is registered asthe service registration status.

There are a variety of methods of registering a service in the serviceregistration status in the user data voice storage database 160; theuser can set it using the communication terminal through the network 170at any time or the user can contract it when the communication terminalis connected to the network 170 or further the operator of the network170 can set it as appropriate.

Then, the operation of the switching system in such a configuration willbe explained using FIG. 5.

FIG. 5 shows a series of processing sequences after a call is connectedfrom the communication terminal 110 to the communication terminal 130using an SIP (Session Initiation Protocol) which is a protocol forsetting a call using an IP telephone, the call is started when the callconnection is completed until the call is disconnected.

First, the procedure after a call is connected between the communicationterminals 110 and 130 until the call is recorded will be explained.

When the user inputs an address of the communication terminal 130 towhich a call connection request is sent, the communication terminal 110sets the address for transmitting/receiving voice data under the controlof the communication terminal overall control section 114, creates aconnection request message of the SIP including this address and theaddress of the communication terminal 130, sets the address of thispacket in the call control apparatus 150 and sends this connectionrequest message to the call control apparatus 150 using thecommunication section 111 (S1000).

Then, upon reception of the connection request message from thecommunication terminal 110 through the communication section 153(S1000), the call control apparatus 150 decides whether thecommunication terminal 130 is connectable or not from the callconnection status of the communication terminal 130 under the control ofthe call control apparatus overall control section 155 and analyzes theaddress when the communication terminal 130 is connectable.

Furthermore, in the example shown in FIG. 4, since the serviceregistration status of the communication terminal 110 controlled by theuser data voice storage database 160 is “CALL RECORDING REGISTERED,” theaddress giving section 154 extracts the address used when thecommunication terminal sends voice data to the call control apparatus150 from among “FREE” addresses in the reception address control tablein FIG. 3 and changes the address status to “BUSY” in the receptionaddress control table.

Furthermore, the call control apparatus 150 changes the destination ofthe connection request message received from the communication terminal110 under the control of the call control apparatus overall controlsection 155 to the communication terminal 130, adds the addressextracted by the address giving section 154 after the area 181 in whichthe connection request message is described as shown in FIG. 6A (S1050),creates a connection request message and sends this message to thecommunication terminal 130 through the communication section 153(S1100).

Then, upon reception of the connection request message from the callcontrol apparatus 150 through the communication section 131 (S1100), thecommunication terminal 130 performs processing such as setting of voicecodec and setting of a voice data destination address in thecommunication terminal 110 set in the received connection requestmessage and setting of a voice data destination address to the callcontrol apparatus 150 in the voice path control section 133 as apreparation for starting a call connection under the control of thecommunication terminal overall control section 134.

Then, the communication terminal 130 sets an address to receive voicedata from the communication terminal 110 under the control of thecommunication terminal overall control section 134, creates a connectionresponse message including this address, designates the call controlapparatus 150 as this destination and sends this connection responsemessage to the call control apparatus 150 using the communicationsection 131 (S1150).

Then, upon reception of the connection response message from thecommunication terminal 130 using the communication section 153 (S150),the call control apparatus 150 sets a port, etc., as a preparation forenabling reception of voice data from the communication terminal underthe control of the call control apparatus overall control section 155.Then the call control apparatus 150 changes the destination of theconnection response message received from the communication terminal 130to the communication terminal 110, adds the address extracted from thereception address control table in FIG. 3 by the address giving section154 after the area 183 in which the connection response message isdescribed as shown in FIG. 6B to thereby create a connection responsemessage and sends this message to the communication terminal 110 usingthe communication section 153 (S1200) Then, upon reception of theconnection response message from the call control apparatus 150 throughthe communication section 111 (S1200), the communication terminal 110performs processing such as setting of voice codec, setting the voicedata destination address to the communication terminal 130 set in thereceived connection response message and the voice data destinationaddress to the call control apparatus 150 in the voice path controlsection 113 as a preparation for starting a call connection under thecontrol of the communication terminal overall control section 114 as inthe case of the communication terminal 130. Then, the communicationterminal 110 creates a connection completion message directed to thecall control apparatus 150 and sends the message to the call controlapparatus 150 using the communication section 111 (S1250).

Then, upon reception of the connection completion message from thecommunication terminal 110 through the communication section 153(S1250), the call control apparatus 150 creates a connection completionmessage with the destination of the received connection completionmessage changed to the communication terminal 130 under the control ofthe call control apparatus overall control section 155 and sends themessage to the communication terminal 130 using the communicationsection 153 (S1300).

Then, when the communication terminal 130 receives this connectioncompletion message (S1300), the call connection is completed.

In such a sequence from S1000 to S1300, the call connection between thecommunication terminal 110 and communication terminal 130 is establishedand four voice paths 191, 192, 193 and 194 are formed as shown in FIG.7. The voice path 191 is a voice path from the communication terminal130 to the call control apparatus 150, the voice path 192 is a voicepath from the communication terminal 110 to the call control apparatus150, the voice path 193 is a voice path from the communication terminal110 to the communication terminal 130 and the voice path 194 is a voicepath from the communication terminal 130 to the communication terminal110.

That is, in the processing of packetizing voice data when voice data ofthe own terminal is sent over the network using the communicationsection 111, the communication terminal 110 creates two identicalpackets using the voice path control section 113, sends one to theaddress of the communication terminal 130 notified with a connectionresponse message from the call control apparatus 150 to thecommunication terminal 110 through the voice path 193 and sends theother to the address of the call control apparatus 150 through the voicepath 192.

Likewise, the communication terminal 130 also creates two identicalpackets of voice data using the voice path control section 133, sendsone to the address of the communication terminal 110 notified with aconnection request message from the call control apparatus 150 to thecommunication terminal 130 through the voice path 194 and sends theother to the address of the call control apparatus 150 through the voicepath 191.

The call control apparatus 150 uses the same address to be used for thevoice paths 191 and 192 and distinguishes the voice data sent from thecommunication terminal 110 from the voice data sent from thecommunication terminal 130 based on the data of the sender of the headerin the packet.

Furthermore, in FIG. 5, direct call processing between the communicationterminal 110 and communication terminal 130 is represented by S1350 andS1400, voice data transmission processing from the communicationterminal 110 to the call control apparatus 150 is represented by S1500and voice data transmission processing from the communication terminal130 to the call control apparatus 150 is represented by S1450.

Furthermore, while the call control apparatus 150 is receiving voicedata from the communication terminals 110 and 130 using thecommunication section 153, that is, for a time until the call of thecommunication terminal 110 or 130 is disconnected, the call controlapparatus 150 performs voice mixing processing on the voice data fromthe communication terminal 110 of “CALL RECORDING REGISTERED” using thevoice mixing section 151 under the control of the call control apparatusoverall control section 155 and stores the mixing data in a storage areaof the communication terminal 110 in the user data voice storagedatabase 160.

Then, the procedure until the call between the communication terminals110 and 130 is disconnected will be explained.

Under the control of the communication terminal overall control section114, triggered by an on-hook operation by the user, etc., thecommunication terminal 110 clears the voice data destination address ofthe communication terminal 130 set in the voice path control section 113and the voice data destination address of the call control apparatus150, etc., as a preparation for disconnecting the call being connected.Then, the communication terminal 110 creates a disconnection requestmessage directed to the call control apparatus 150 and sends it to thecall control apparatus 150 using the communication section 111 (S1550).

Then, upon reception of the disconnection request message from thecommunication terminal 110 through the communication section 153(S1550), the call control apparatus 150 changes the destination of thereceived disconnection request message to the communication terminal 130under the control of the call control apparatus overall control section155 and sends this disconnection request message to the communicationterminal 130 using the communication section 153 (S1600).

Then, upon reception of the disconnection request message from the callcontrol apparatus 150 through the communication section 131 (S1600),under the control of the communication terminal overall control section134, the communication terminal 130 clears the voice data destinationaddress of the communication terminal 110 set in the voice path controlsection 133 and the voice data destination address of the call controlapparatus 150, etc., as a preparation for disconnecting the call beingconnected. Then, the communication terminal 130 creates a disconnectionresponse message directed to the call control apparatus 150 and sendsthe message to the call control apparatus 150 using the communicationsection 131 (S1650).

Then, upon reception of the disconnection response message from thecommunication terminal 130 through the communication section 153(S1650), under the control of call control apparatus overall controlsection 155, the call control apparatus 150 changes the destination ofthe received disconnection response message to the communicationterminal 110 and sends this disconnection response message to thecommunication terminal 110 using the communication section 153 (S1750).Furthermore, at this time, the address giving section 154 changes theaddresses set for the voice paths 191 and 192 in the reception addresscontrol table (see FIG. 3) from “BUSY” to “FREE” (address release)(S1700).

Then, the communication terminal 110 receives the disconnection responsemessage from the call control apparatus 150 through the communicationsection 111 (S1750).

According to such a sequence from S1550 to S1750, the call between thecommunication terminals 110 and 130 is disconnected and at the sametime, the voice data directed to the call control apparatus 150 of boththe communication terminals 110 and 130 is no longer sent and the callcontrol apparatus 150 stops the call recording.

Finally, the procedure for playbacking the voice data stored in the userdata voice storage database 160 will be explained (not shown).

In the case where the voice data stored in the user data voice storagedatabase 160 is playbacked, when the user keys in data from the playbacksection 112, that is, makes a PB (Push Button) entry, this triggers thecommunication terminal 110 to create a playback request message in whichthe own terminal address for receiving the stored voice data is setunder the control of the communication terminal overall control section114 and send the message to the call control apparatus 150 using thecommunication section 111.

Then, upon reception of the playback request message from thecommunication terminal 110 using the communication section 153, underthe control of the call control apparatus overall control section 155,the call control apparatus 150 extracts the voice data from the storagearea (see FIG. 4) in the user data voice storage database 160 of thecommunication terminal 110 which sent the playback request using thevoice playback control section 152 and sends the voice data to thecommunication terminal 110 using the communication section 153.

Then, upon reception of the voice data from the call control apparatus150 through the communication section 111, the communication terminal110 playbacks the received voice data using the playback section 112under the control of the communication terminal overall control section114.

As shown above, when the communication terminal 110 (or 130) transmitsthe voice data of the own terminal over the network while a call isconnected, the switching system of this embodiment provides the voicepath control sections 113 and 133 that create two identical voicepackets, send one to the call control apparatus 150 and the otherdirectly to the communication terminal 130 (or 110) on the other end,provides the call control apparatus 150 with the voice mixing section151 that mixes the voice data sent to the own address and stores thevoice data in the user data voice storage database 160, and can therebyrealize call recording.

This allows voice data of a communication terminal with which a call isconnected to be sent directly to another communication terminal on theother end without passing through the call control apparatus, shortensthe time interval between transmission of voice data and reception ofthe voice data and increases the number of communication terminalscontrollable by the call control apparatus compared to the case wherethe call control apparatus is involved in transmission/reception ofvoice data between the communication terminals.

This embodiment assumes as a precondition that negotiation informationis exchanged to perform bidirectional communication such as voice codecwith a connection message for a call connection.

Furthermore, for the method of voice mixing at the voice mixing section151 of the call control apparatus 150, an existing technology can beused.

Furthermore, the configuration of this embodiment can be changed invarious ways.

That is, in this embodiment, each communication terminal and callcontrol apparatus are connected to the network through independentswitches, but of the communication terminals and call control apparatusa plurality of apparatuses may also be connected to the network throughthe same switch.

Furthermore, this embodiment has described the case where the protocolused for a call connection is an SIP, but the operation of thisembodiment is also possible using other protocols.

Furthermore, this embodiment has been explained assuming that timing tostart call recording is registered in the call control apparatusbeforehand, but this embodiment can also be adapted in such a way thatthe user who uses a communication terminal carrying outtransmission/reception of voice data while a call is connected startscall recording by means of key input, etc., during the call as requiredand terminates the call recording before the call is disconnected usinga similar method.

Furthermore, this embodiment has described the case where when theservice registration status of the communication terminal 110 is “CALLRECORDING REGISTERED,” voice data after voice mixing is stored in thestorage area of the communication terminal 100, but this embodiment isnot limited to this and when, for example, both the service registrationstatuses of the communication terminals 110 and 130 are “CALL RECORDINGREGISTERED,” it is possible to store the voice data after voice mixingin the storage area of one communication terminal in the user data voicestorage database and a duplicate of the data in the storage area of theother communication terminal.

Embodiment 2

This embodiment will describe a switching system in which a call betweencommunication terminals is carried out through a multicast voice pathand a call control apparatus acquires the call voice from this multicastvoice path and records the call voice. The multicast is broadcastingamong some communication terminals connected to a LAN or the Internetand broadcasting is applied to only communication terminals joining amulticast group.

FIG. 8 shows a switching system of this embodiment. Communicationterminals 210 and 230 correspond to the communication terminals 110 and130 according to Embodiment 1 shown in FIG. 2 with the voice pathcontrol sections removed. Furthermore, a call control apparatus 250 isprovided with a multicast address giving section 251 instead of theaddress giving section 154 in Embodiment 1 shown in FIG. 2, which sets amulticast address for calls between the communication terminals 210 and230 and controls the multicast address so as to be used for callrecording. Furthermore, switches 200, 220 and 240 are switchesapplicable to multicast. The rest of the configuration is the same asthat in Embodiment 1 (see FIG. 2).

The functions of the communication terminals 210 and 230 and callcontrol apparatus 250 are implemented by causing computers incorporatedin these apparatuses to execute processing specified by a program.

FIG. 9 shows a multicast address control table controlled by themulticast address giving section 251. As shown in FIG. 9, this controltable describes a multicast address used for calls between thecommunication terminals 210 and 230 and their utilization statuses.

A user data voice storage database 160 stores the content shown in FIG.10 as in the case of Embodiment 1 (see FIG. 4).

Then, the operation of the switching system in the above configurationwill be explained using FIG. 11.

FIG. 11 shows a series of processing sequences after a call is connectedfrom the communication terminal 210 to the communication terminal 230using an SIP, the call is started when the call connection is completeduntil the call is disconnected.

First, the procedure after a call is connected between the communicationterminals 210 and 230 until the call is recorded will be explained.

When the user inputs an address of the communication terminal 230 towhich a call connection request is sent, under the control of acommunication terminal overall control section 211, the communicationterminal 210 creates a connection request message directed to the callcontrol apparatus 250 and sends this connection request message to thecall control apparatus 250 using a communication section 111 (S2000).

Then, upon reception of the connection request message from thecommunication terminal 210 through a communication section 153 (S2000),the call control apparatus 250 decides whether the communicationterminal 230 is connectable or not from the call connection status ofthe communication terminal 230 under the control of a call controlapparatus overall control section 252 and analyzes the address when thecommunication terminal 230 is connectable.

Furthermore, in the example shown in FIG. 10, since the serviceregistration status of the communication terminal 210 controlled by theuser data voice storage database 160 is “CALL RECORDING REGISTERED,” themulticast address giving section 251 selects and extracts the multicastaddress used by the communication terminal for a call from among “FREE”addresses in the multicast address control table in FIG. 9 and changesthe address status to “BUSY” in the multicast address control table.

Furthermore, the call control apparatus 250 changes the destination ofthe connection request message received from the communication terminal210 under the control of the call control apparatus overall controlsection 252 to the communication terminal 230, adds the multicastaddress to an area 262 after an area 261 in which the connection requestmessage is described as shown in FIG. 12A (S2050), creates a connectionrequest message and sends this message to the communication terminal 230through the communication section 153 (S2100). Furthermore, the callcontrol apparatus 250 joins a multicast group indicated by the multicastaddress.

Then, upon reception of the connection request message from the callcontrol apparatus 250 through the communication section 131 (S2100), thecommunication terminal 230 performs processing such as setting of voicecodec, setting of the multicast address set in the received connectionrequest message and processing of joining the multicast group (S2150) asa preparation for starting a call connection under the control of acommunication terminal overall control section 231. This multicastaddress becomes the address of the communication terminal 210 to whichthe voice data is to be sent and the address of the call controlapparatus 250 to which the voice data is to be sent.

Then, the communication terminal 230 creates a connection responsemessage directed to the call control apparatus 250 under the control ofthe communication terminal overall control section 231 and sends thisconnection response message to the call control apparatus 250 using thecommunication section 131 (S2200).

Then, upon reception of the connection response message from thecommunication terminal 230 using the communication section 153 (S2200),the call control apparatus 250 sets a port, etc., as a preparation forenabling the voice data from the communication terminal to be receivedunder the control of the call control apparatus overall control section252. Then, the call control apparatus 250 changes the destination of theconnection response message received from the communication terminal 230to the communication terminal 210, the multicast address giving section251 adds the multicast address extracted from the multicast addresscontrol table in FIG. 9 after an area 263 in which the connectionresponse message is described as shown in FIG. 12B to thereby create aconnection response message and sends this message to the communicationterminal 210 using the communication section 153 (S2250).

Then, upon reception of the connection response message from the callcontrol apparatus 250 through the communication section 111 (S2250), thecommunication terminal 210 performs processing such as setting of voicecodec, setting of the multicast address set in the received connectionrequest message as the address of the communication terminal 230 towhich the voice data is to be sent and the address of the call controlapparatus 250 to which the voice data is to be sent and processing ofjoining a multicast group (S2300) as a preparation for starting a callconnection under the control of the communication terminal overallcontrol section 211 as in the case of the communication terminal 230.Then, the communication terminal 210 creates a connection completionmessage directed to the call control apparatus 250 and sends the messageto the call control apparatus 250 using the communication section 111(S2350).

Then, upon reception of the connection completion message from thecommunication terminal 210 through the communication section 153(S2350), the call control apparatus 250 creates a connection completionmessage with the destination of the received connection completionmessage changed to the communication terminal 230 under the control ofthe call control apparatus overall control section 252 and sends themessage to the communication terminal 230 using the communicationsection 153 (S2400).

Then, when the communication terminal 230 receives this connectioncompletion message (S2400), the call connection is completed.

In such a sequence of S2000 to S2400, the call connection between thecommunication terminal 210 and communication terminal 230 is establishedand multicast voice paths 271 and 272 are formed as shown in FIG. 13.FIG. 11 shows the call processing through the multicast voice paths 271and 272 as S2450 and S2500.

Furthermore, while the call control apparatus 250 is receiving voicedata sent from the communication terminals 210 and 230 through thecommunication section 153 using a multicast address, that is, for a timeuntil the calls of the communication terminals 210 and 230 aredisconnected, the call control apparatus 250 performs voice mixingprocessing on the voice data from the communication terminal 210 whichis in a status “CALL RECORDING REGISTERED” under the control of the callcontrol apparatus overall control section 252 using the voice mixingsection 151 and stores the mixing data in a storage area of thecommunication terminal 210 in the user data voice storage database 160.

Then, the procedure until the connection between the communicationterminals 210 and 230 is disconnected will be explained.

Under the control of the communication terminal overall control section211, triggered by an on-hook operation by the user, etc., thecommunication terminal 210, for example, withdraws from the multicastgroup (S2550) as a preparation for disconnecting the call beingconnected. Then, the communication terminal 210 creates a disconnectionrequest message directed to the call control apparatus 250 and sends itto the call control apparatus 250 using the communication section 111(S2660).

Then, upon reception of the disconnection request message from thecommunication terminal 210 through the communication section 153(S2600), the call control apparatus 250 changes the address of thereceived disconnection request message to the communication terminal 230under the control of the call control apparatus overall control section252 and sends this disconnection request message to the communicationterminal 230 using the communication section 153 (S2650).

Then, upon reception of the disconnection request message from the callcontrol apparatus 250 through the communication section 131 (S2650),under the control of the communication terminal overall control section231, the communication terminal 230, for example, withdraws from themulticast group (S2700) as a preparation for disconnecting the callbeing connected. Then, the communication terminal 230 creates adisconnection response message directed to the call control apparatus250 and sends the message to the call control apparatus 250 using thecommunication section 153 (S2750).

Then, upon reception of the disconnection response message from thecommunication terminal 230 through the communication section 153(S2750), under the control of call control apparatus overall controlsection 252, the call control apparatus 250 changes the destination ofthe received disconnection response message to the communicationterminal 210 and sends this disconnection response message to thecommunication terminal 210 using the communication section 153 (S2850).Furthermore, at this time, the multicast address giving section 251changes the multicast address acquired from the multicast addresscontrol table (see FIG. 9) from “BUSY” to “FREE” (address release)(S2800) and the call control apparatus 250 withdraws from the multicastgroup.

Then, the communication terminal 210 receives the disconnection responsemessage from the call control apparatus 250 through the communicationsection 111 (S2850).

According to such a sequence from S2600 to S2850, the call between thecommunication terminals 210 and 230 is disconnected and at the sametime, the voice data directed to the call control apparatus 250 of boththe communication terminals 210 and 230 is no longer sent and the callcontrol apparatus 250 stops the call recording.

Here, the series of processes of playbacking voice data stored in theuser data voice storage database 160 in this switching system is thesame as that in Embodiment 1.

As shown above, in the switching system of this embodiment, the callcontrol apparatus 250 is provided with the section 251 that controls andadds a multicast address for call recording and when a call connectionrequest is received from the communication terminal 210 (or 230), thesection 251 selects a multicast address and notifies it to all thecommunication terminals 230 (210) involved in the call connection andthe call control apparatus 250 joins the multicast group indicated bythe address. While a call is connected, the communication terminal 210(or 230) transmits all voice data using the address and the call controlapparatus 250 mixes the voice packet directed to itself sent to theaddress and stores the voice packet in the user data voice storagedatabase 160. Call recording is performed in this way.

This causes the voice data of the communication terminal with which thecall is connected to be sent directly to the communication terminal onthe other end without passing through the call control apparatus,shortens the time interval between transmission of voice data andreception of the voice data and increases the number of communicationterminals controllable by the call control apparatus compared to thecase where the call control apparatus is involved intransmission/reception of voice data between the communicationterminals.

This embodiment has described the case where the call control apparatusspecifies a multicast address to be used for both a call betweencommunication terminals and call recording of the call controlapparatus, but this embodiment can also be adapted in such a way thatthe communication terminal which sends a call holds an availablemulticast address beforehand, notifies the multicast address to thecommunication terminal and call control apparatus on the call receivingside to thereby realize a call between the communication terminals andits call recording or the call receiving side carries out the sameprocedure.

The various modifications shown in Embodiment 1 are also applicable tothis embodiment.

Embodiment 3

This embodiment will describe a switching system in which acommunication terminal having a reception buffer directly communicateswith a terminal on the other end, stores the voice data on the other endin the reception buffer and sends the voice data in the buffer to a callcontrol apparatus after the call is disconnected and stores the voicedata.

As shown in FIG. 14, this switching system is provided with receptionbuffers 311 and 331 that temporarily store the voice data received bythe communication terminals 310 and 330. The rest of the configurationis the same as that of Embodiment 1 (see FIG. 2).

The functions of the communication terminals 310 and 330 and callcontrol apparatus 350 are implemented by causing computers incorporatedin these apparatuses to execute processing specified by a program.

Then, the operation of this switching system will be explained usingFIG. 15.

FIG. 15 shows a series of processing sequences after a call is connectedfrom the communication terminal 310 to the communication terminal 330using an SIP, the call is started when the call connection is completeduntil the call is disconnected.

The processing from S3000 to S3250 until a call is connected between thecommunication terminals 310 and 330 is the same as that from S1000 toS1300 in Embodiment 1 shown in FIG. 5. However, in FIG. 15, addressgiving processing at a call control apparatus 350 is omitted for thesake of convenience.

Through such a sequence from S3000 to S3250, a call connection betweenthe communication terminal 310 and communication terminal 330 isestablished and two voice paths 361 and 362 are formed during a call asshown in FIG. 16. The voice path 361 is a voice path from thecommunication terminal 310 to the communication terminal 330 and thevoice path 362 is a voice path from the communication terminal 330 tothe communication terminal 310. In FIG. 15, call processing through thevoice paths 361 and 362 are shown by S3300 and S3350.

During a call, upon reception of voice data sent from the communicationterminal 330 using a communication section 111, the communicationterminal 310 stores the voice data in the reception buffer 311 under thecontrol of a communication terminal overall control section 312 andoutputs the voice data to a speaker or receiver attached to thecommunication terminal 310. Furthermore, the communication terminal 330also performs similar processing.

Then, the processing until a call is disconnected between thecommunication terminals 310 and 330 will be explained.

Under the control of the communication terminal overall control section312, triggered by an on-hook operation by the user, etc., thecommunication terminal 310 prepares for a disconnection of the callbeing connected, creates a disconnection request message directed to thecall control apparatus 350 and sends the message to the call controlapparatus 350 using the communication section 111 (S3400). Then, thecommunication terminal 310 stops receiving voice data sent from thecommunication terminal 330 with which the call is connected and at thesame time stops storage in the reception buffer 311.

Then, upon reception of the disconnection request message from thecommunication terminal 310 through a communication section 153 (S3400),under the control of a call control apparatus overall control section351, the call control apparatus 350 creates a disconnection requestmessage with the destination of the received disconnection requestmessage changed to the communication terminal 330 and sends the messageto the communication terminal 330 using the communication section 153(S3450).

Then, upon reception of the disconnection request message from the callcontrol apparatus 350 through a communication section 131 (S3450), underthe control of a communication terminal overall control section 332, thecommunication terminal 330 prepares for a disconnection of the callbeing connected, creates a disconnection response message directed tothe call control apparatus 350 and sends the message to the call controlapparatus 350 using the communication section 131 (S3500).

Then, triggered by the transmission of the above disconnection responsemessage from the communication section 131, the communication terminal330 stops receiving voice data sent from the communication terminal 310with which the call is connected and stops storage in the receptionbuffer 331 and at the same time sends the voice data in the receptionbuffer 331 using the communication section 131 directed to the addressof the call control apparatus 350 notified through the connectionrequest message in S3050 (buffer content transfer) (S3550). Thistransmission continues as long as voice data exists in the receptionbuffer 331.

Then, upon reception of the disconnection response message from thecommunication terminal 330 through the communication section 153(S3500), under the control of the call control apparatus overall controlsection 351, the call control apparatus 350 creates a disconnectionresponse message with the destination of the received disconnectionresponse message changed to the communication terminal 310 and sends themessage to the communication terminal 310 using the communicationsection 153 (S3600).

Then, triggered by the reception of the disconnection response messagefrom the call control apparatus 350 through the communication section111, the communication terminal 310 sends the voice data in thereception buffer 311 to the address of the call control apparatus 350notified through the connection response message in S3150 using thecommunication section 111 (buffer content transfer) (S3650). Thistransmission continues as long as voice data exists in the receptionbuffer 311.

Then, when the communication section 153 starts to receive the voicedata sent from the communication terminal 310 and communication terminal330, under the control of the call control apparatus overall controlsection 351, the call control apparatus 350 mixes the two pieces ofvoice data using the voice mixing section 151 and stores voice data fromthe communication terminal 310 in a status, for example, “CALL RECORDINGREGISTERED” as the voice data of call recording in a storage area of thecommunication terminal 310 in the user data voice storage database 160(see FIG. 17). Furthermore, when the communication section 153 confirmsthe stoppage of the transmission of the voice data from both thecommunication terminal 310 and communication terminal 330, the callcontrol apparatus 350 stops the storage in the user data voice storagedatabase 160 and uses the address giving section 154 to set the addressnotified to the communication terminal when the connection requestmessage and connection response message are sent to “FREE” in theaddress control table in FIG. 3.

Here, the series of processes of playbacking voice data stored in theuser data voice storage database 160 in this switching system is thesame as that in Embodiment 1.

As shown above, in the switching system of this embodiment, thecommunication terminals 310 and 330 are provided with the receptionbuffers 311 and 331 to store voice data of the terminal on the otherend, the communication terminal sends the voice data of the own terminaldirectly to the terminal on the other end while a call is connected andstores the voice data likewise sent from the communication terminal onthe other end in the reception buffer. Then, after the call isdisconnected, the voice data in the reception buffers 311 and 331 of therespective communication terminals 310 and 330 is packetized and sent tothe call control apparatus 350 and the call control apparatus 350 mixesthe received packets and stores them in the user data voice storagedatabase 160 to thereby realize call recording.

This allows the voice data of the communication terminal with which acall is connected to be sent directly to the communication terminal onthe other end without passing through the call control apparatus,thereby shortens the time interval between transmission of voice dataand reception of the voice data and increases the number ofcommunication terminals controllable by the call control apparatuscompared to the case where the call control apparatus is involved intransmission/reception of voice data between the communicationterminals.

This embodiment sends the content of the reception buffer of thecommunication terminal to the call control apparatus triggered by adisconnection of a call, but this embodiment can be modified in manyways, for example, by sending the content of the reception buffer usingthe time zone corresponding to the lowest traffic of the network on theday, etc.

Furthermore, this embodiment has described the case where the receptionbuffer of a communication terminal stores voice data received fromanother terminal on the other end, but this embodiment can also beadapted so that each communication terminal stores voice data sent fromthe own terminal and sends this voice data to the call control apparatusafter the call is disconnected.

The various modifications shown in Embodiment 1 are also applicable tothis embodiment.

Furthermore, when the user who uses a communication terminal with whicha call is connected keys in data during the call and sends a callrecording request message to a call control apparatus and specifies thestart of call recording, it is possible to notify the user of theaddress used in the call recording through a response message, etc.,from the call control apparatus.

Embodiment 4

This embodiment will describe a switching system in which acommunication terminal having a reception buffer directly communicateswith a terminal on the other end, stores voice data of both the terminalon the other end and the own terminal in a reception buffer, mixes thevoice data in the buffer after the call is disconnected, sends the voicedata to a call control apparatus to store the voice data.

As shown in FIG. 18, this switching system is provided with voice mixingsections 411 and 431 whereby communication terminals 410 and 430 mixvoice data stored in reception buffers 311 a and 331 a and own voicereception sections 412 and 432 that copy the voice data input by theuser, store one in the reception buffers 311 a and 331 a and sends theother to the communication terminal on the other end with which a callis connected. A call control apparatus 450 includes no voice mixingsection. The rest of the configuration is the same as that of Embodiment3 (see FIG. 14).

However, the reception buffers 311 a and 331 a temporarily store thevoice data sent from the communication terminal on the other end while acall is connected and then received by communication sections 111 and131 and also temporarily store a copy of the voice data sent from theown voice reception sections 412 and 432 and to be sent to thecommunication terminal on the other end by the own communicationterminal.

The functions of the communication terminals 410 and 430 and callcontrol apparatus 450 are implemented by causing computers incorporatedin these apparatuses to execute processing specified by a program.

Then, the operation of this switching system will be explained usingFIG. 19.

FIG. 19 shows a series of processing sequences after a call is connectedfrom the communication terminal 410 to the communication terminal 430using an SIP, the call is started when the call connection is completeduntil the call is disconnected.

The processing from S4000 to S4250 until a call is connected between thecommunication terminals 410 and 430 is substantially the same as S1000to S1300 in Embodiment 1 shown in FIG. 5 with the only difference inthat a connection request message sent from the call control apparatus450 to the communication terminal 430 in S4050 is not assigned any voicedata reception address acquired from an address control table. However,a connection response message sent from the call control apparatus 450to the communication terminal 410 in S4150 is assigned this voice datareception address. The communication terminal 410 notified of the voicedata reception address stores the partner's voice data and the own voicedata in the reception buffer 311 a, mixes the voice data in thereception buffer 311 a after the call is disconnected and sends themixed voice data to the call control apparatus 450. However, thecommunication terminal 430 which is not notified of the voice datareception address does not perform such processing.

Through such a sequence from S4000 to S4250, the call connection betweenthe communication terminal 410 and communication terminal 430 isestablished and two voice paths 461 and 462 are formed during the callas shown in FIG. 20. The voice path 461 is a voice path from thecommunication terminal 410 to the communication terminal 430 and thevoice path 462 is a voice path from the communication terminal 430 tothe communication terminal 410. In FIG. 19, call processing through thevoice paths 461 and 462 is shown by S4300 and S4350.

Being notified of the address of the call control apparatus 450 throughthe connection response message in S4150, upon reception of voice datafrom the communication terminal 430 during a call, the communicationterminal 410 stores the voice data received through the communicationsection 111 in the reception buffer 311 a under the control of thecommunication terminal overall control section 413 and outputs the voicedata to a speaker or receiver attached to the communication terminal410.

Furthermore, when the communication terminal 410 sends the voice data ofthe user who uses the communication terminal 410 to the communicationterminal 430, the own voice reception sections 412 and 432 copy thevoice data input by the user, stores one of this voice data in thereception buffer 311 a and sends the other to the communication terminalon the other end 430 using the communication section 111 through thevoice path 461 under the control of the communication terminal overallcontrol section 413.

On the other hand, the communication terminal 430 which has not beennotified of the address of the call control apparatus 450 through theconnection request message in S4050 does not store the voice data in thereception buffer 331 a. The rest of the processing is similar to that ofthe communication terminal 410.

Then, the processing until the call between the communication terminals410 and 430 is disconnected will be explained.

Under the control of the communication terminal overall control section413, triggered by an on-hook operation by the user, etc., thecommunication terminal 410 prepares for a disconnection of the callbeing connected, creates a disconnection request message directed to thecall control apparatus 450 and sends the message to the call controlapparatus 450 using the communication section 111 (S4400). Then, thecommunication terminal 410 stops receiving the voice data sent from thecommunication terminal 430 with which the call is connected and at thesame time stops all the storage in the reception buffer 311 a.

Then, upon reception of the disconnection request message from thecommunication terminal 410 through a communication section 153 (S4400),under the control of a call control apparatus overall control section451, the call control apparatus 450 changes the destination of thereceived disconnection request message to the communication terminal 430and sends this message to the communication terminal 430 using thecommunication section 153 (S4450).

Then, upon reception of the disconnection request message from the callcontrol apparatus 450 through the communication section 131 (S4450),under the control of the communication terminal overall control section433, the communication terminal 430 prepares for a disconnection of thecall being connected, creates a disconnection response message directedto the call control apparatus 450 and sends the message to the callcontrol apparatus 450 using the communication section 131 (S4500).

Then, upon reception of the disconnection response message from thecommunication terminal 430 through the communication section 153(S4500), under the control of the call control apparatus overall controlsection 451, the call control apparatus 450 creates a disconnectionresponse message with the destination of the received disconnectionresponse message changed to the communication terminal 410 and sends themessage to the communication terminal 410 using the communicationsection 153 (S4550).

Then, upon reception of the disconnection response message from the callcontrol apparatus 450 using the communication section 111, thecommunication terminal 410 mixes two types of voice data stored in thereception buffer 311 a using the voice mixing section 411 and sends thevoice data to the address of the call control apparatus 450 notifiedthrough the connection response message in S4150 using the communicationsection 111 (buffer content transfer) (S4600). This transmissioncontinues as long as voice data exists in the reception buffer 311 a.

Then, when the communication section 153 starts to receive the voicedata sent from the communication terminal 410, under the control of thecall control apparatus overall control section 451, the call controlapparatus 450 stores the voice data as the voice data of call recordingin a storage area of the communication terminal 410 in the user datavoice storage database 160 (see FIG. 21). Furthermore, when thecommunication section 153 confirms the stoppage of the transmission ofthe voice data from the communication terminal 410, the call controlapparatus 450 stops the storage in the user data voice storage database160 and sets to “FREE” in the address control table in FIG. 3 theaddress notified to the communication terminal 410 when the connectionresponse message is sent using an address giving section 154.

Here, the series of processes of playbacking voice data stored in theuser data voice storage database 160 in this switching system is thesame as that in Embodiment 1.

As shown above, the switching system of this embodiment provides thecommunication terminals 410 and 430 with the reception buffers 311 a and331 a and voice mixing sections 411 and 431, stores voice data of theown terminal in the own terminal area in the reception buffer, sends thevoice data directly to the terminal on the other end while a call isconnected and stores the voice data sent from the communication terminalon the other end in the area for the terminal on the other end of thereception buffer. Then, after the call is disconnected, the voice datain the respective areas in the reception buffers 311 a and 331 a ismixed and the mixed data is packetized and sent to the call controlapparatus 450. Then, the call control apparatus 450 receives the packet,stores the packet in the user data voice storage database 160 andthereby realizes call recording.

This allows the voice data of the communication terminal with which acall is connected to be sent directly to the communication terminal onthe other end without passing through the call control apparatus andthereby shortens the time interval between transmission of voice dataand reception of the voice data. Furthermore, the call control apparatusonly needs to control the content of call recording mixed by thecommunication terminal and requires no processing such as voice mixinginvolved in call recording and thereby further increases the number ofcommunication terminals controllable by the call control apparatus.

The various modifications shown in Embodiment 3 are also applicable tothis embodiment.

As is clear from the above explanations, the switching system of thepresent invention can directly transmit/receive voice data betweencommunication terminals without passing through the call controlapparatus and record the content of the call through the call controlapparatus. This makes it possible to reduce delays of voice datatransmitted/received between the communication terminals and avoidunnatural conversations such as the voice of the party on the other endbeing heard with a delay.

The present invention can also reduce the burden on the call controlapparatus and increase the number of communication terminalscontrollable by the call control apparatus.

This application is based on the Japanese Patent Application No.2001-397265 filed on Dec. 27, 2001, entire content of which is expresslyincorporated by reference herein.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a switching system which switchesvoice calls, etc., carried out between communication terminals throughthe Internet and LAN, etc.

1. A switching system that connects a plurality of communicationterminals by the medium of a call control apparatus having a callrecording function through a network, each of said plurality ofcommunication terminals comprising: a first acquisition section thatacquires a multicast address; and a formation section that forms voicepaths through multicasting to transmit/receive voice data to/from acommunication terminal on the other end based on the acquired multicastaddress, and said call control apparatus comprising: a notificationsection that notifies said plurality of communication terminals of themulticast address; a second acquisition section that joins themulticasting to acquire voice data sent through the multicasting fromeach of said plurality of communication terminals; and a mixing/storagesection that mixes and stores the acquired voice data.
 2. The switchingsystem according to claim 1, wherein said network is an IP network andsaid plurality of communication terminals performs packet communicationwith one another through the IP network.
 3. A communication terminalused in a switching system that connects a plurality of communicationterminals by the medium of a call control apparatus having a callrecording function through a network, comprising: an acquisition sectionthat acquires a multicast address; and a formation section that formsvoice paths through multicasting to transmit/receive voice data to/froma communication terminal on the other end based on the acquiredmulticast address.
 4. A call control apparatus used in a switchingsystem that connects a plurality of communication terminals by themedium of a call control apparatus having a call recording functionthrough a network, comprising: a notification section that notifies saidplurality of communication terminals of a multicast address; anacquisition section that joins multicasting to acquire voice data sentthrough the multicasting from each of said plurality of communicationterminals; and a mixing/storage section that mixes and stores theacquired voice data.
 5. A call recording method in a switching systemthat connects a plurality of communication terminals by the medium of acall control apparatus having a call recording function through anetwork, comprising: a notifying step of said call control apparatusnotifying said plurality of communication terminals of a multicastaddress; a first acquiring step of said plurality of communicationterminals acquiring the multicast address notified from said callcontrol apparatus; a forming step of said plurality of communicationterminals each forming voice paths through multicasting totransmit/receive voice data to/from a communication terminal on theother end based on the multicast address acquired in said firstacquiring step; a second acquiring step of said call control apparatusjoining the multicasting to acquire voice data sent through themulticasting from each of said plurality of communication terminals; anda mixing/storing step of said call control apparatus mixing and storingthe voice data acquired by said second acquisition section.